Characterizing the urban temperature trend using seasonal unit root analysis: Hong Kong from 1970 to 2015

This paper explores urban temperature in Hong Kong using long-term time series. In particular, the characterization of the urban temperature trend was investigated using the seasonal unit root analysis of monthly mean air temperature data over the period January 1970 to December 2013. The seasonal unit root test makes it possible to determine the stochastic trend of monthly temperatures using an autoregressive model. The test results showed that mean air temperature has increased by0.169?C(10 yr)~(-1)over the past four decades. The model of monthly temperature obtained from the seasonal unit root analysis was able to explain 95.9% of the variance in the measured monthly data — much higher than the variance explained by the ordinary least-squares model using annual mean air temperature data and other studies alike. The model accurately predicted monthly mean air temperatures between January 2014 and December 2015 with a root-mean-square percentage error of 4.2%.The correlation between the predicted and the measured monthly mean air temperatures was 0.989. By analyzing the monthly air temperatures recorded at an urban site and a rural site, it was found that the urban heat island effect led to the urban site being on average 0.865?C warmer than the rural site over the past two decades. Besides, the results of correlation analysis showed that the increase in annual mean air temperature was significantly associated with the increase in population, gross domestic product, urban land use, and energy use, with the R~2 values ranging from 0.37 to 0.43.     

公开DEM辅助无地面控制点国产卫星影像定位方法

在全球测绘的背景下,为实现无地面控制点的卫星摄影测量,提出了利用公开DEM辅助国产卫星影像进行无控定位的方法。为充分利用公开DEM在大范围内具有一致稳定的高精度特性,将其作为基准与从影像中提取的待定位DEM进行表面匹配,匹配时采用引入截尾最小二乘估计的最小高差(LZD)法,并根据对应点高差的分布自适应探测及剔除DEM之间的差异;匹配确定的变换参数用于对直接定位结果进行物方改正。设计了多组针对天绘一号和资源三号国产卫星影像的对比试验,结果表明本方法切实可行,能充分利用基准DEM的优势,具有较好的稳健性;定位精度很大程度上取决于但不限于基准DEM的精度,基本不受其分辨率的影响;当待定位DEM分辨率较高时,单景影像利用SRTM DEM即可得到能较好满足1∶5万比例尺地形图测制要求的无控定位精度。本方法还为卫星影像定位精度的检核提供了一种新的有效手段。     

Isoprenoids of Okinawan mangroves as lipid input into estuarine ecosystem

Isoprenoids in the nonsaponifiable lipids (NSL) fraction of Okinawan mangroves were analyzed with special reference to their importance as lipid input into estuarine ecosystems. Triterpenoids and phytosterols comprised the major proportion of NSL. Identifications of the triterpenoids and phytosterols in NSL fraction were based on the interpretation of ¹³C-NMR and GC-MS spectra. The triterpenoids and phytosterols mainly comprised 11 and 6 compounds, respectively. The major components were lupeol, β-amyrin and taraxerol for triterpenoids, and β-sitosterol and stigmasterol for phytosterols. The diversity in the terpenoid composition was noted in both leaves and roots of mangrove species, implying the chemotaxonomic utility of terpenoids. Terpenoid compositions of the root are not always similar to that of leaf, suggesting that terpenoids in the root are produced by biosynthesis in situ, not by translocation of the synthate from the leaf. Terpenoids existed in greater proportion in the outer parts of the root. These data are likely to contribute to estimating the lipid input from mangrove trees adjacent to estuarine sediments and the ocean.     

线性模型下的不完全样本

设有线性模型Y=xβ+ε,这里Y是一个m维随机向量,x是一个已知m×p阵,ε是一个m维随机误差向量,E_ε=0,V_(αγε)=σ~2Im,β和σ~2>0都是未知的。设我们得到子样Y_1,Y_2,…,Y_n,由于某些原因,Y_i(i=1,2,…,n)的某些分量得不到,我们称此为不完全样本。本文得到了所有β的可估线性函数、所有叶估线性函数的LSE以及基于残差的σ~2的无偏估计在完全样本与不完全样本下相同的充要条件。     

增长曲线模型非齐次线性估计的可容许性

本文讨论了增长曲线模型中回归矩阵的函数的估计 ,在矩阵损失下 ,作者得到了非齐次线性估计在非齐次线性估计类中可容许的充要条件。     

误差方差二次型估计模型的转化

研究一般的回归模型中误差方差的二次型估计的容许性，研究方法是模型的整体转化和局部转化，结果有：（１）二次约束下的线性模型等价于相应的无约束的线性模型。（２）线性（齐次或非齐次）等式约束下的线性模型等价于某个无约束的线性模型。（３）单个非齐次不等式约束下的线性模型等价于某个无约束的线性模型。（４）通过例子证明了多个线性不等式约束的线性模型不能等价于某个无约束的线性模型。（５）某类非齐次二次型估计的容许性等价于相应的齐次二次型估计的容许性     

Hedgerow impacts on soil-water transfer due to rainfall interception and root-water uptake

Hedgerow is one of the most important rural landscapes in the world, especially in Europe. Knowledge about the hydrological role of hedgerows is useful in many fields of study, such as hydrological modelling and rural landscape management. The aim of this study was to investigate the impact of a hedgerow on rainfall distribution, soil-water potential gradient, lateral water transfer and water balance. A hillslope with a hedgerow perpendicular to the slope was monitored. To evaluate hedgerow rainfall interception, rainfall was measured (hourly, daily, and by rainfall event) both next to and up to 16 m upslope and 12 m downslope perpendicularly away from the hedgerow. The strongest correlation between rainfall next to the hedgerow and rainfall at more distant points was obtained using data measured per rainfall event. The average percentage of rainfall intercepted equalled 28% for the leafed period and 12% for the leafless period. The impact of the hedgerow on spatial rainfall distribution was related to distance from the hedgerow and rainfall amount. Annual distribution of soil-water potential showed that the hedgerow influenced it up to 9 m upslope and 6 m downslope, the area in which most of the hedgerow's roots were observed. The soil was driest at the end of summer, which delayed soil rewetting during autumn in areas surrounding the hedgerow. Annual groundwater dynamics exhibited three distinct periods due to temporal rainfall distribution and, especially at the end of summer, root-water uptake. In addition, the total potential gradient showed that unsaturated flow was directed towards the hedgerow in summer and autumn. These results indicate that at the local scale hedgerows influences (1) spatial rainfall distribution, (2) soil rewetting, and (3) groundwater recharge, often at distances well beyond the hedgerow's drip line. Consequently, the processes involved in soil-water dynamics around hedgerows should be integrated into relevant hydrological models, especially for catchments with a dense hedgerow network. Copyright © 2008 John Wiley & Sons, Ltd.     

Soil water dynamics and water balance on a tropical coral island

Understanding soil water dynamics and the water balance of tropical coral islands is important for the utilization and management of their limited freshwater resources, which is only from rainfall. However, there is a significant knowledge gap in the influence of soil water on the water cycle of coral islands. Soil water dynamics and the water balance of Zhaoshu Island, Xisha Archipelago were thus investigated using soil moisture measurements and the Hydrus-1D model from October 2018 to September 2019. Over the study period, vegetation transpiration, soil evaporation, groundwater recharge and storage in the vadose zone were approximately 196, 330, 365 and 20 mm, occupying 22%, 36%, 40% and 2% of annual rainfall total (911 mm), respectively. For the wet season (from May to October) these values became 75, 202, 455 and 40 mm, occupying 10%, 26% and 59% and 5% of the seasonal rainfall total (772 mm), respectively. During the dry season (from November to April), a dry soil layer between 40 and 120 cm depth of the soil profile was identified that prevented water exchange between the upper soil layers and the groundwater resulting in the development of deep roots so that vegetation could extract groundwater to supplement their water requirements. Vegetation not only consumes all dry season rainfall (140 mm) but extracts water deeply from groundwater (90 mm) as well as from the vadose layer (20 mm). As such, the vegetation appears to be groundwater-dependent ecosystems. The research results aid us to better understand the process of water dynamics on coral islands and to protect coral island ecosystems.     

Remote sensing and ground‐based measurements of evapotranspiration in an extreme cold Patagonian desert

Accurate estimates of seasonal evapotranspiration (ET) at different temporal and spatial scales are essential for understanding the biological and environmental determinants of ecosystem water balance in arid regions and the patterns of water utilization by the vegetation. For this purpose, remote sensing ET estimates of a Patagonian desert in Southern Argentina were verified with field measurements of soil evaporation and plant transpiration using an open top chamber. Root distribution and seasonal variation in soil volumetric water content were also analysed. There was a high correlation between remote sensing and field measurements of ecosystem water fluxes. A substantial amount of the annual ET occurred in spring and early summer (73.4 mm) using winter rain stored in the soil profile and resulting in water content depletion of the upper soil layers. A smaller amount of annual ET was derived from few rainfall events occurring during the mid or late summer (41.4 mm). According to remote sensing, the 92.9% of the mean annual precipitation returns to the atmosphere by transpiration or evaporation from the bare soil and by canopy interception. Only 7.1% infiltrates to soil layers deeper than 200 cm contributing to the water table recharge. Fourier time series analysis, cross‐correlation methods and multiple linear regression models were used to analyse 11 years of remote sensing data to assess determinants of water fluxes. A linear model predicts well the variables that drive complex ecosystem processes such as ET. Leaf area index and air temperature were not linearly correlated to ET because of the multiple interaction among variables resulting in time lags with ET variations and thus these two variables were not included in the linear model. Soil water content, the fraction of photosynthetic active radiation and precipitation explained 86% of the ET monthly variations. The high volumetric water content and the small seasonal variations at 200‐cm depth were probably the result of little water uptake from deeper soil horizons by roots with low hydraulic conductivity. Copyright © 2016 John Wiley & Sons, Ltd.     

地铁盾构隧道各阶段平面控制测量的限差分配

结合＂城市轨道交通工程测量规范＂中的相关技术要求,从理论上分析盾构隧道横向贯通误差的主要来源及各阶段平面控制测量误差限值的合理分配,并针对盾构法施工地铁隧道的特点,探讨长大盾构区间地面平面控制点的布设原则及限值的优化配赋。